Deflect Missiles, one of the Ancient Curses, protects against damage from Ranged attacks and can deflect some of the damage back onto the attacker.

The deflection curses are a primary reason for players to switch from the normal prayer set to the curses, as they have the same drain rate as the protection prayers from the regular book and can deal additional damage back.

Deflect curses will grant you 50% damage reduction against most attacks from players and monsters. Deflect curses have a chance to reflect damage back at your attacker, and the damage reflected is 10% of the damage the attack would have done if not blocked by the deflect curse.